45 results about "Rabi frequency" patented technology

The invention discloses an electromagnetic field near-field imaging system and method based on pulsed light detection magnetic resonance. The system consists of a laser pump optical path, a microwave source, a diamond NV color-center probe, a CCD camera unit, a synchronization system, a displacement scanning platform, control software and a data analysis imaging system. In the system, a large diamond single crystal containing the NV color-center is used as a detection unit, a static magnetic field is used to split a magnetic resonance peak of the diamond NV color-center into eight peaks, the eight resonance peaks correspond to four crystal axis directions <111>, <1-11>, <-111>, <11-1> of a diamond lattice structure, by measuring the Rabi frequency of each resonance peak, the strength of a circularly polarized microwave field perpendicular to the corresponding crystal axis direction is obtained, and through comprehensive calculation of the microwave field strengths in the four directions, the strength and direction of a microwave vector are then reconstructed. Through the microwave near-field high-resolution imaging of a local region of a microwave chip under measurement, the quantitative data can be provided for the failure analysis of the chip.

This invention relates generally to NMR systems for in vivo detection of analytes. More particularly, in certain embodiments, the invention relates to systems in which superparamagnetic nanoparticles are exposed to a magnetic field and radio frequency (RF) excitation at or near the Larmor frequency, such that the aggregation and / or disaggregation of the nanoparticles caused by the presence and / or concentration of a given analyte in a biological fluid is detected in vivo from a monitored RF echo response.

This invention relates generally to NMR systems for in vivo detection of analytes. More particularly, in certain embodiments, the invention relates to systems in which superparamagnetic nanoparticles are exposed to a magnetic field and radio frequency (RF) excitation at or near the Larmor frequency, such that the aggregation and / or disaggregation of the nanoparticles caused by the presence and / or concentration of a given analyte in a biological fluid is detected in vivo from a monitored RF echo response.

Methods and systems are provided to reduce stimulated Brillouin scattering in high power optical fiber amplifiers. In an embodiment, a seed source includes a narrow linewidth semiconductor laser driven with a current ramp that simultaneously sweeps the optical power and the lasing frequency at a rate fast enough to reduce stimulated Brillouin scattering.

Method and apparatus for testing a directional acoustic device such as a directional hearing aid having level-dependent non-linear circuitry, in which two or more speakers are placed at desired positions relative to the hearing aid, e.g. in front and behind the hearing aid. The speakers are excited simultaneously with broadband excitation signals formed from components which are orthogonal to each other, e.g. sinusoids, where the bin frequencies of the Direct Fourier Transform (“DFT”) of one excitation signal are different from the bin frequencies of the other excitation signal. Thus, the response to each excitation signal can easily be extracted without filtering, allowing the directional characteristics of the hearing aid to be evaluated.

In a radiation-pressure elastography technique for transmitting a ultrasound focused beam into a test object body and diagnosing the hardness thereof, it is required to consider high sensitivity and safety.In the present invention, the focused beam is transmitted to two positions as a means for displacing a tissue and exciting a shear wave. In addition, time control is performed in such a manner that a transmit beam serves as a burst-chirp signal, and ultrasound waves are transmitted and received while sweeping a transmit frequency. On this occasion, when the distance between the two focused points and the transmit frequency become integral multiple of the wavelength, two waves interfere with each other, thereby obtaining a large amplitude. Furthermore, when the transmit frequency becomes equal to a resonance frequency peculiar to the tissue, the amplitude also becomes larger. Accordingly, a small intensity of transmit waveform enhances sensitivity. In addition, transmission using the burst-chirp signal facilitates widening of a bandwidth of the transmit frequency, enabling usage of a frequency highly sensitive for a target measurement site. Optional number of focused points and arbitrary positions thereof allow a wide area to be covered.

A tunable lasing device (100) comprising a ring-shaped laser cavity (102), an optical gain element (104), a bi-directional output coupler (106) and a frequency selection means (114). The frequency selection means is generally a grating with a refractive index that determines a grating reflection frequency. Single mode laser operation is achieved where a cavity mode frequency of the ring-shaped laser cavity coincides with a grating reflection frequency. The refractive index of the grating can be modified by the injection of a variable current. In this way, the lasing frequency can be rapidly tuned between cavity mode frequencies.

Methods and systems are provided to reduce stimulated Brillouin scattering in high power optical fiber amplifiers. In an embodiment, a seed source includes a narrow linewidth semiconductor laser driven with a current ramp that simultaneously sweeps the optical power and the lasing frequency at a rate fast enough to reduce stimulated Brillouin scattering.

A normally opaque waveguide interacting with a drop-filter cavity can be switched to a transparent state when the drop filter is also coupled to a dipole. This dipole induced transparency may be obtained even when the vacuum Rabi frequency of the dipole is much less than the cavity decay rate. The condition for transparency is a large Purcell factor. Dipole induced transparency can be used in quantum repeaters for long distance quantum communication.

An electromagnetic frequency filter comprises a resonator (15) which is arranged between and close to an input waveguide (13) and an output waveguide (14) and resonant with an electromagnetic wave of a certain frequency. The output waveguide (14) is so formed that it is parallel to the input waveguide (13) in a certain area (18) near the resonator (15) while it is at a farther distance from the input waveguide (13) in the area other than the certain area (18) when compared with the distance between the two waveguides in the certain area (18). This electromagnetic frequency filter can be preferably formed using a two-dimensional photonic crystal.

The invention provides a noise detector for porous metal composite arrayed electrets. According to the feature that a great amount of communicated voids exist in a porous metal material composite structure, when sound wave propagates in the material, sound energy under certain frequency is continuously consumed by air glutinousness and thermal conduction of the material; the sounds under different frequencies are treated in a classified manner; accordingly, interference of various stray waves is effectively reduced. One of two sets of synchronous sound acquisition sensors in the same type is packaged and isolated from external high-frequency signals and serves as low-frequency background noise for monitoring signals, the sensors are alternately arranged at intervals in an array manner, acquired signals are fused and filtered in a controller and are subjected to background subtraction with low-frequency signals acquired other ways around a sampling point, the low-frequency background noise is deducted by spectrum transformation, and the direction of a noise source is judged according to the intensity and phase change of signals acquired by arrayed noise monitors mounted in different directions.

A linear method for measuring the radiation EMI in GIEM chamber includes putting the object (EUT) to be measured on an turntable in GTEM chamber, determining the relative relation between various axises of EUT and various axises of GTEM chamber, rotating the turntable by alpha angle counterclockwise, measuring 6 data at a certain frequency but different 6 positions, using the linear equations set to find out the equivalent electric and magnetic couple moments, and calculating the radiated field intensify in wide field.

The invention discloses a synchronization self-adaptation short-wave communication frequency-selecting method based on ionized layer data. The synchronization self-adaptation short-wave communication frequency-selecting method based on the ionized layer data comprises the step one that the maximum usable frequency of a channel is obtained by utilizing the ionized layer data according to short-wave communication link timing, wherein the ionized layer data comprise real-time observational data, historical data and the like; the step two that the range of usable frequency is determined according to the maximum usable frequency and by combining communication efficiency and / or duration of passable frequency; the step three that the range of the usable frequency is sent to a synchronization self-adaptation short-wave communication system; the step four that the synchronization self-adaptation short-wave communication system obtains the optimum usable frequency by scanning the range of usable frequency in a synchronization self-adaptation frequency-selecting mode, and then communication can be carried out. The synchronization self-adaptation short-wave communication frequency-selecting method based on the ionized layer data can overcome the defect in the prior art that the efficiency is low or it is difficult to obtain the optimum usable frequency due to the fact that channel information needs to be set in advance, and can efficiently select the optimum communication frequency. Thus, the synchronization self-adaptation short-wave communication frequency-selecting method based on the ionized layer data has an obvious effect on improvement of comprehension effectiveness of short-wave data communication.

The invention relates to a Ka frequency range miniaturization broadband multimode auto-tracking feed source network. Two polarization degenerate modes of TE21 mode transmitted by center circular waveguide are coupled to four rectangular waveguide by adopting a four-arm circular polarization TE21 coupler. Two four-way polarization degenerate modes of the TE21 mode is combined into two two-way polarization degenerate modes of the TE21 mode by two broadband magic Ts. A left-handed or right-handed circular polarization difference mode is output by a broadband 90-degree electrical bridge. The TE21 coupler center circular waveguide is capable of simultaneously transmitting a TE11 mode. Due to the fact that the TE21 coupler is connected with a broadband circular polarization machine, and two polarization modes of a signal are respectively output from two ports of the broadband circular polarization machine, the Ka frequency range miniaturization broadband multimode auto-tracking feed source network is capable of simultaneously receiving a signal of double-circular polarization and a difference signal, and thereby the auto-tracking function is realized. The Ka frequency range miniaturization broadband multimode auto-tracking feed source network has the advantages of not only simplifying composition of the feed source network, reducing the volume and the weight of the whole device, but also reducing network construction, saving feed source cost and broadening working band of the feed source network.

Embodiments of the present invention provide a waveguide plasma limiter and a design method thereof, which relate to the field of electromagnetic pulse protection and can effectively resist high-power microwave weapons. The design method includes: determining the cut-off frequency fc and cross-sectional dimensions a, b of the rectangular waveguide according to the frequency f of the normal transmission signal, wherein fc=0.9f, b=0.3a-0.5a; determining the plasma frequency fp is less than the cut-off frequency fc is greater than the high-power microwave frequency fHPM, and the filling gas and the gas pressure of the filling gas under the condition of t<tr; the thickness of the filling gas is calculated

The invention provides a method for pre-stack CRP trace gather frequency-broadening processing. The method can maintain a good signal to noise ratio while improving the resolution of a seismic time profile according to spectrum characteristics of seismic waves, and can enable the resolution and the signal to noise ratio to be well combined. The method comprises the following steps of step one: using logging information and seismic traces by a well to perform inversion of a target layer section; step two: calculating a seismic wavelet according to the target layer number in the step one; step three: calculating the energy and frequency distribution range of an initial CRP trace gather; step four: obtaining the type of noise according to the energy and frequency distribution range of the initial CRP trace gather; step five: selecting a typical trace and determining an effective wave main energy distribution space; step six: determining a CRP frequency-broadening operator according to the energy and frequency distribution range of the initial CRP trace gather and the effective wave main energy distribution space; and step seven: performing CRP trace gather frequency-broadening processing according to the seismic wavelet, the type of noise and the CRP frequency-broadening operator. The method can maintain a good signal to noise ratio, and is high in reliability, good in stability and substantial in effect.

The invention discloses a biological feedback headache treating instrument, which is provided with a vibration gyroscope, a control unit, a low-frequency electrotherapy unit, wherein the vibration gyroscope is used for detecting the head movement of a human body; the control unit is communicated with the vibration gyroscope; and the low-frequency electrotherapy unit is used for emitting low-frequency pulse current. During use, the control unit is used for receiving and analyzing head vibration signals uploaded by the vibration gyroscope. When the generating frequency of the head vibration signals exceeds a certain frequency within a certain time threshold, the control unit is used for controlling the low-frequency electrotherapy unit to output pulse current for treating a user. According to the technical scheme, biological feedback technology is applied to the biological feedback headache treating instrument and a headache medical system based on an Internet of things technology, so that the electrocerebral information of a current user can be obtained effectively through real-time cerebral cortex detection; and by comparing with pre-stored relevant information of current, the headache condition of the user can be judged accurately, and high reliability is achieved.